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[flang] Skip optimized bufferization on volatile refs #140781

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[flang] Skip optimized bufferization on volatile refs #140781

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f84c4cc
[flang] Skip optimized bufferization on volatile refs
ashermancinelli May 20, 2025
8b8ff48
Check for null effect value instead of volatile resource
ashermancinelli May 20, 2025
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6 changes: 6 additions & 0 deletions flang/lib/Optimizer/HLFIR/Transforms/OptimizedBufferization.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -608,6 +608,12 @@ ElementalAssignBufferization::findMatch(hlfir::ElementalOp elemental) {
return std::nullopt;
}

if (effect.getValue() == nullptr) {
LLVM_DEBUG(llvm::dbgs()
<< "side-effect with no value, cannot analyze further\n");
return std::nullopt;
}

// allow if and only if the reads are from the elemental indices, in order
// => each iteration doesn't read values written by other iterations
// don't allow reads from a different value which may alias: fir alias
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49 changes: 49 additions & 0 deletions flang/test/HLFIR/opt-bufferization-skip-volatile.fir
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@@ -0,0 +1,49 @@
// RUN: fir-opt --pass-pipeline="builtin.module(func.func(opt-bufferization))" %s | FileCheck %s

// Ensure optimized bufferization preserves the semantics of volatile arrays
func.func @minimal_volatile_test() {
%c1 = arith.constant 1 : index
%c200 = arith.constant 200 : index

// Create a volatile array
%1 = fir.address_of(@_QMtestEarray) : !fir.ref<!fir.array<200xf32>>
%2 = fir.shape %c200 : (index) -> !fir.shape<1>
%3 = fir.volatile_cast %1 : (!fir.ref<!fir.array<200xf32>>) -> !fir.ref<!fir.array<200xf32>, volatile>
%4:2 = hlfir.declare %3(%2) {fortran_attrs = #fir.var_attrs<volatile>, uniq_name = "_QMtestEarray"} : (!fir.ref<!fir.array<200xf32>, volatile>, !fir.shape<1>) -> (!fir.ref<!fir.array<200xf32>, volatile>, !fir.ref<!fir.array<200xf32>, volatile>)

// Create an elemental operation that negates each element
%5 = hlfir.elemental %2 unordered : (!fir.shape<1>) -> !hlfir.expr<200xf32> {
^bb0(%arg1: index):
%6 = hlfir.designate %4#0 (%arg1) : (!fir.ref<!fir.array<200xf32>, volatile>, index) -> !fir.ref<f32, volatile>
%7 = fir.load %6 : !fir.ref<f32, volatile>
%8 = arith.negf %7 : f32
hlfir.yield_element %8 : f32
}

// Assign the result back to the volatile array
hlfir.assign %5 to %4#0 : !hlfir.expr<200xf32>, !fir.ref<!fir.array<200xf32>, volatile>
hlfir.destroy %5 : !hlfir.expr<200xf32>

return
}

fir.global @_QMtestEarray : !fir.array<200xf32>

// CHECK-LABEL: func.func @minimal_volatile_test() {
// CHECK: %[[VAL_0:.*]] = arith.constant 200 : index
// CHECK: %[[VAL_1:.*]] = fir.address_of(@_QMtestEarray) : !fir.ref<!fir.array<200xf32>>
// CHECK: %[[VAL_2:.*]] = fir.shape %[[VAL_0]] : (index) -> !fir.shape<1>
// CHECK: %[[VAL_3:.*]] = fir.volatile_cast %[[VAL_1]] : (!fir.ref<!fir.array<200xf32>>) -> !fir.ref<!fir.array<200xf32>, volatile>
// CHECK: %[[VAL_4:.*]]:2 = hlfir.declare %[[VAL_3]](%[[VAL_2]]) {fortran_attrs = #fir.var_attrs<volatile>, uniq_name = "_QMtestEarray"} : (!fir.ref<!fir.array<200xf32>, volatile>, !fir.shape<1>) -> (!fir.ref<!fir.array<200xf32>, volatile>, !fir.ref<!fir.array<200xf32>, volatile>)
// CHECK: %[[VAL_5:.*]] = hlfir.elemental %[[VAL_2]] unordered : (!fir.shape<1>) -> !hlfir.expr<200xf32> {
// CHECK: ^bb0(%[[VAL_6:.*]]: index):
// CHECK: %[[VAL_7:.*]] = hlfir.designate %[[VAL_4]]#0 (%[[VAL_6]]) : (!fir.ref<!fir.array<200xf32>, volatile>, index) -> !fir.ref<f32, volatile>
// CHECK: %[[VAL_8:.*]] = fir.load %[[VAL_7]] : !fir.ref<f32, volatile>
// CHECK: %[[VAL_9:.*]] = arith.negf %[[VAL_8]] : f32
// CHECK: hlfir.yield_element %[[VAL_9]] : f32
// CHECK: }
// CHECK: hlfir.assign %[[VAL_5]] to %[[VAL_4]]#0 : !hlfir.expr<200xf32>, !fir.ref<!fir.array<200xf32>, volatile>
// CHECK: hlfir.destroy %[[VAL_5]] : !hlfir.expr<200xf32>
// CHECK: return
// CHECK: }
// CHECK: fir.global @_QMtestEarray : !fir.array<200xf32>